For long time politicians have been using every single way possible to get peoples attention, along with big expensive campaigns, behind the public and direct propaganda, they create indirect propaganda, sometimes supporting them and sometimes attacking their campaigns, philosophies, resources etc... but always being a resource to keep people talking about them.
An example of Art use by politicians to reach their goal is Copley's painting of Samuel Adams(1770), where we see Adams standing behind a desk holding the petition to England to expel their troops from Massachusetts; now we admired this painting as part of the American history, but going back then this painting was just a way for Adams to show his success, let's no forget that he was one of the architects of the principles of American Republicanism that shaped the political culture of the United States.
Now lets flip the coin and talk about the most recent Art/political events. In 2008 Barack Obama was elected President of US, which is definitely one of the most influential events of our times, the firs no White President, and finally our country realizing that we are more than Race, ethnicity, Sex Gender, we are all human being and the most smart creature on Earth, I personally feel very proud of being part of this generation it doesn't matter how bad things can go, now days every time more people react and start appreciating the most simple and important things of live and our world.
Part of the indirect Obama Campaign was the utilization of one of his picture turned into an Art piece, then turned into a big creation of T-shirts by a very "smart" Brand, the T-shirts became part of the Pop Culture and a Great advertising campaign, we also heard a lot of singers, singing and writing song to express they feeling for the back then candidate, Celebrities talking about Obama philosophy, all one big massive campaign.
Art is an expression of feelings, social changes create feelings in people, and these people express their feelings through Art.